JPH0784847B2 - Two-cycle internal combustion engine and operating method thereof - Google Patents

Abstract

The engine, operating on the two-stroke cycle, is characterised in that the admission and exhaust distributing elements are valves (7, 9), their control elements being sensitive to a parameter such as the speed of rotation of the engine, the fuel consumption, the supercharging pressure value, the difference between intake and exhaust pressure, in order to vary the angular opening and closing position of the valves (7, 9) to ensure that a sufficient quantity of fresh air is admitted into the working chamber, under the least favourable conditions, in particular by opening the intake during a period when the volume of the chamber is increased. <IMAGE>

Description

The present invention comprises at least one variable volume working chamber defined by a piston and having at least one air inlet and at least one gas outlet, and two cycles. The invention relates to an internal combustion engine that is driven by.

The engine related to the present invention is composed of a turbo compressor unit, that is, a turbine operated by exhaust gas of an engine, and its outlet is mechanically connected to a supercharged compressor having a single outlet or a communication with the outlet of each working chamber. It is preferred, but not necessary, to be supercharged by a turbocompressor unit connected to the.

An internal combustion engine with at least one variable volume working chamber, i.e. a working chamber defined by a moving device (e.g. piston) cooperating with a fixed unit (e.g. cylinder), always having two separate stages. Is the process of shutting down the working chamber from the air intake and gas exhaust system by the simultaneous closing of the intake and exhaust timing elements, and the nature of the forced work received by the shaft of the engine. A stage referred to as the closing stage, where compression, combustion and expansion of the parts take place, and a gas exchange opening stage in which the working chamber is in communication with the intake and / or exhaust system.

For all engines of this type, this open stage is the period during which pressure is released in a single or in each working chamber, which discharges the working chamber at the end of the expansion stage of the closing stage and the discharge timing element. It is carried out by opening it so that it communicates only with the discharge system. This release period is often termed in English as "exhaust blast" or "pulse". During this period, the pressure in the working chamber, which is increased by the heating of the gas provided by the combustion, is much higher than the pressure in the exhaust system (usually
Due to the fact that it has a ratio on the order of 2 to 3), a sonic expansion then a subsonic expansion occurs, during which a large proportion (more than half) of the gas contained in the working chamber is transferred to the exhaust system. To be done.

In a four-cycle engine, a portion of the remaining gas is forced out by the piston after the expulsion period and then
Fresh air is drawn in by the piston during the volume increase of the working chamber. On the other hand, in a two-cycle engine, the release of the gas remaining in the working chamber after the release period and its replacement with fresh air is due to the simultaneous opening of the intake and exhaust timing elements during a period called the scavenging period, which causes the gas dynamics. Will be achieved. The effectiveness of this scavenging determines the efficiency and performance of the two-stroke engine. Various scavenging systems have been proposed in this regard, especially the use of valves in two-stroke engines as intake and exhaust elements.

However, in order to effectively achieve this scavenging, the pressure immediately upstream of the working chamber or chambers, i.e., the pressure of the intake system during scavenging under all operating conditions of the engine, immediately downstream of the exhaust system There should be a higher average pressure. Therefore, two-cycle engines have hitherto required a pressure generator to average this pressure differential and maintain a positive value during the scavenging period.

These pressure generators are kinematic pistons used in double-acting type, for example those which cooperate with a chamber located below its lower side (for example by means of a crosshead piston) or a main shaft. Formed by a piston which cooperates with the fixed case of, in conjunction with sufficient timing elements, to pre-compress air before it is introduced into the working chamber, or on the main shaft. Auxiliary booster elements that are mechanically linked, such as positive displacement vane compressors or roots compressors,
Alternatively, it is formed independently of the rotation of the main shaft, for example, by an electrically driven one.

From an economic standpoint, these various pressure generators
It adversely affects the size of the engine with accessories and the energy consumption when these devices are utilized.

In the case of a two-cycle engine supercharged by a turbo compressor, the positive pressure difference between the upstream side and the downstream side of the working chamber, which is necessary for scavenging the working chamber during the scavenging period, means that the engine has high power. Naturally guaranteed by the supercharged turbo compressor when operating at. In fact, when the compressor is operated at a sufficient pressure ratio, the expansion ratio of the turbine required for stable driving of the turbocompressor is low, and the efficiency of the turbocompressor and the gas temperature at the outlet of the working chamber are high. So, for example, with an overall efficiency of 60%, modern turbocompressors with turbines supplied with 4 bar gas at 600 ° C are designed to deliver 5 bar air from 20 ° C atmospheric pressure. ,
The working chamber is therefore naturally subject to a positive pressure difference of 1 bar.

On the other hand, when the supercharged two-cycle engine is operated at low power, the enthalpy in the discharge portion of the working chamber is not enough for the supercharged turbine to drive the compressor at a speed that maintains the positive pressure difference. It is enough. As a result, if the auxiliary device is not provided, fresh air will flow into the working chamber.
The reverse pressure differential that prevents reintroduction of the engine will cause the engine to shut down. For even stronger reasons the engine cannot be started.

These accessories are of the pressure-generating type described above. These devices may be of the type that operate the turbocompressor independently of the engine at a speed that prevents reversal of the pressure differential between upstream and downstream in the working chamber. Thus, for example, the outlet of the compressor can be connected to the inlet of the turbine and a bypass conduit associated with the auxiliary combustion chamber can be provided and the speed of the turbo compressor will be lower than the previously determined threshold value. An adjusting device can be provided to prevent this.
Alternatively, an auxiliary turbine wheel supplied with pressure fluid, for example a Pelton fluid turbine, can be added to the turbocompressor.

However, these adjuncts are complex and costly and increase fuel consumption when they are utilized.

It is therefore an object of the present invention to provide a two-stroke engine that does not have an external scavenger other than a supercharged turbo compressor for starting and low power operation.

Another object of the invention is, but is not limited to, that it is preferable to have a single or each working chamber of a supercharged two-stroke engine, when this engine is operated at low power and at its start-up. , Is to introduce fresh air naturally without adding the above-mentioned accessory device.

Another object of this invention is to utilize at least part of the energy in the single or downstream of each working chamber to facilitate the introduction of this fresh air.

Another object of the present invention is to accelerate the rotor of a supercharged turbocompressor when it is deployed, by opening the exhaust timing element to increase energy either alone or downstream of each working chamber. It is easy.

Another object of the invention is to improve the torque curve of the engine.

The present invention is to provide an internal combustion engine which has at least one variable volume working chamber defined by a piston in a cylinder without lateral ports and which is operated in two cycles, the engine being operated by a turbo compressor. However, the gas inlet of the turbine is communicated with the gas outlet of the working chamber, and the air of the compressor mechanically driven by the turbine is also provided. The outlet is in communication with the air inlet of the working chamber, and in this engine, the air inlet and the gas outlet of the working chamber are provided with intake and exhaust valves that are synchronized with the rotation of the engine shaft. Along with that, because the engine does not have an external scavenger for starting and low power operation, The intake and exhaust valves are to be actuated by a control device capable of changing the angular position of the opening and closing of the valve as viewed from the shaft of the engine as a function of at least one operating parameter of the engine, and Responds to the operating parameters of the engine and advances the opening start of the intake valve during start-up and low power operation and maintains it at least 20 ° after the opening start of the exhaust valve for normal operating conditions, for full operation. A sufficient amount of fresh air can be introduced into the single or each working chamber over the conditions.

In the present invention, the device for controlling the intake and exhaust valves is capable of adjusting the opening angular position of its opening and closing over a wide angular range.

The field of the invention therefore eliminates the timing element which is provided in a normal two-cycle engine and which is provided in the fixed wall of the cylinder and which is exposed by the piston periodically during its travel. is doing. In this case, the angular opening and / or closing position is in fact determined once relative to the position of the kinematic piston, and necessarily for the whole, and corresponds to the maximum volume of the working chamber called bottom dead center (BDC). It is symmetrical with respect to the piston position and the port is designed to communicate the working chamber with the outside.

The valve is based on French patent 2,338, filed January 15, 1976.
It is particularly advantageous to configure it as described in 385.

In the present invention, the engine operating parameter means a detectable parameter that is related to the operation of the engine and can take at least two values.
That one value is sufficient to ensure that the value of the pressure difference between the upstream or intake side and the downstream or exhaust side of the working chamber is kept positive and that it ensures good operation of the engine. Is a value and therefore corresponds to the operation of the engine during the period in which the engine is operating as a normal two-cycle engine under normal operating conditions, and the other value is the magnitude at which the pressure difference is insufficient or It corresponds to the operation of the engine during periods when the air pressure difference simply does not exist, as in the case of negative or stopped engines.

This parameter can be, for example: supercharging pressure value in the case of a supercharged two-cycle engine; the amount of fuel introduced into a single or multiple working chambers per cycle, rotation of the main shaft of the engine The effective difference value between the speed, the temperature at the exhaust manifold, the intake and exhaust pressures, preferably between the pressure upstream and downstream of the working chamber.

The control device responsive to said parameters by the detection device and controlling the operation of the intake and exhaust valves can be of any type. It can be of the mechanical type, for example, and can be driven directly by the main shaft of the engine, for example in the case of a camshaft, via a motion chain. In this case, mechanical or other adjusting devices are provided for adjusting the angular open and closed positions of the intake and exhaust valves.

Said control device may be of the electric, fluid or pneumatic type and may be synchronous with the rotation of the main shaft of the engine, and the regulating device responsive to said parameters may also include the angular opening and closing of intake and exhaust valves. The position can be adjusted.

Thus, in accordance with the present invention, the engine operates in the normal operating range as well as various types of two-stroke engines that may or may not be supercharged. On the other hand, its operating conditions are adjusted to effectively guarantee or replace scavenging when operating outside the normal operating range. This is achieved mainly by utilizing a part of the process of increasing the volume of each working chamber, i.e. the process of intake of air, by correspondingly changing the angular opening and closing positions of the intake and exhaust valves.

Therefore, at least during the cycle of opening the intake valve,
For example, the kinematic piston of the working chamber is significantly advanced near the intermediate stroke and the timing of the discharge valve is adjusted accordingly. Thus, the amount of fresh air available for combustion is increased, and advancing the closing of the intake and exhaust valves increases the volumetric compression ratio, which facilitates self-ignition when desired in diesel engines, if desired.

Further, advancing the exhaust in the cycle increases the energy of the exhaust blast that occurs at high pressures and temperatures. In the case of a two-cycle engine that is turbo fed by a turbo compressor unit and whose turbine that drives the compressor is itself driven by the exhaust gas, the exhaust system directly connects the exhaust valve and the turbine wheel. Advantageously. Then, at very low speeds, the blast pulse spins the turbocompressor unit at a slow speed, which vents the working chamber without supercharging the engine air, thereby exhausting combustion gases from it and the fresh air. Will be exchanged sufficiently.

This direct connection can be easily ensured by using an exhaust pipe that is regularly bent and opens into the exhaust manifold, the passage section of the exhaust manifold is for high speed and high flow rate, The axial plast pulse does not introduce any obstruction and the manifold is passed through the turbine wheel without intervening distributors.

In a special embodiment of the invention, the angular position is arranged such that the intake and exhaust valves are at least approximately not simultaneously in the open position.

In another embodiment of the invention, the intake and exhaust valves are opened simultaneously, in which case the unidirectional device limits or prevents the possibility of gas in the exhaust system backflowing into a single or each working chamber. Is arranged in the exhaust section.

In this embodiment, a check valve or other mechanical non-return device may be utilized in the exhaust, but the inertia effect of the gas column being moved through the pipe connecting the gas outlet of the working chamber to the gas manifold. Alternatively, the ejection effect generated by the gas pulse from the working chamber may be utilized upon emptying the other working chamber in the scavenging condition, in this latter case preferably a large number of working chambers of 4 or more are used. You will need it.

When exhaust gas inertia is utilized, it is useful to provide a device that provides unidirectional flow in the exhaust system, especially in the pipe that connects the gas outlet of the single or multiple working chambers with the gas manifold, The unidirectional device preferably comprises, for example, a sufficiently long stationary exhaust pipe and its outlet is oriented in the same direction as the gas flow in the manifold.

The ejection effect brought about by the gas pulse is also
In particular, when the number of working chambers is 4 or more, in order to make the gas outlets of the single or plural working chambers communicate with the gas manifold,
It has a converging / diverging nozzle shape and its outlet is oriented in the same direction as the gas flow in the manifold, and
It is preferably utilized by providing a pipe coaxial with the manifold.

In the latter case, the case manifold is provided with a substantially constant passage section which, under normal operating conditions, has a sufficiently small passage section such that the gas flow velocity at the downstream end of the manifold exceeds Mach number 0.4. There is. The downstream outlet of the gas manifold is connected to the turbine inlet of the turbocompressor of the supercharged engine via a diffusion device that reduces the flow velocity to a Mach number less than 0.4. Alternatively, the downstream outlet of the gas manifold is in direct communication with the gas inlet of the turbine of the supercharged turbocompressor unit and its gas distribution spiral shape is between the outlet of the manifold and the inlet to the turbine rotor. It is constructed so that the speed is not reduced.

The present invention also provides a method for operating the aforementioned two-cycle engine.

The first operating method has the following characteristics: a) When the above-mentioned parameter or parameters have values corresponding to normal or nominal operating conditions of the engine, the engine is composed of Operated in the usual way with a two-cycle engine: a compression-combustion-expansion stage with the intake and exhaust valves closed, a pulsed (pulsating) exhaust period at the end of the expansion stage with only the exhaust valve open, intake and Scavenging, during which the exhaust valves are simultaneously opened, during which combustion gas is replaced with fresh air by the effect of at least partly, on average or positive pressure difference on each side of each working chamber. Duration; b) On the other hand, when the operating parameter has a value corresponding to an operating condition in which the engine is not operating or operating properly, the valve opening angle The position is advanced to a single or maximum working volume position of each working chamber so that communication between the working chamber and the intake system of the engine takes place mainly during part of the working chamber volume increasing period. In particular, if there is a stage where the intake and exhaust valves are open at the same time, place a pipe that connects the working chamber with the gas manifold to create a substantial backflow from the gas manifold in the direction of a single or each working chamber. You can avoid it.

The operating angular positions of the intake and exhaust valves are sharply modified when the parameters pass a predetermined threshold. Optionally, multiple consecutive thresholds may be provided for multiple rapid corrections of the valve position.

Alternatively, the angular position is modified by a continuous or quasi-continuous function of the parameters described above to cause a progressive change between a position corresponding to favorable driving conditions and a position corresponding to unfavorable driving conditions. You can

In a two-cycle engine, it is known that only the intake air or the exhaust air is carried out through a valve that performs adjustable timing operation, and in that case, the exhaust air or the intake air is delivered through a fixed port that is not covered by a piston. Please note that this is achieved.

On the other hand, the present invention can temporarily achieve the four-cycle effect by opening the intake valve that precedes the opening of the exhaust valve but follows it. And this effect is the engine (US-A-2,09) with its intake opening specified and therefore with an intake port that cannot be preceded.
7,883 engines (except FIG. 6) and engines with exhaust ports preceded by intake opening but not followed by exhaust (US-A-2,097,883, 6th).
(Fig.) Is not possible.

In particular, during normal operation of the engine of the present invention, the effective stroke (in compression) of the engine of the present invention is at least 50% of the total stroke of a single or each piston. In start-up or low-power operating mode, the intake stroke is at least 50% of the total stroke, the compression stroke is on the order of 100% of this stroke, and the angular discrepancy OE-OA is 20% (crankshaft rotation Angle) is greater than or equal to.

In a normal two-cycle engine equipped with an intake port and a variable timing exhaust valve, it is impossible to increase the intake stroke because it is a fixed intake port, and for the same reason, the compression stroke is partially increased. It is possible, that is, it cannot reach 100%.

In a normal two-cycle engine with an exhaust port and variable timing intake valve, the intake stroke can be increased at the expense of the OE (exhaust release) -OA (intake open) discrepancy. Therefore, the exhaust blast is discharged to the intake side and, as a result, the engine is choked. Moreover, due to the fixed exhaust port, the compression stroke cannot reach 100%.

Further, it has been proposed to operate the engine alternately by two cycles and by four cycles, that is, in the state where there is no continuous or gradual change between the two operation modes (see JP-A-58-152139). ).

The invention also relates to a method of starting such an engine, in which, when starting, the engine is operating according to one of the methods described above, and when the motor is supercharged, the supercharged turbo compressor unit It has the feature of being accelerated before the engine starts.

Further advantages and features of the invention will become apparent from the following description, by way of non-limiting example, with reference to the drawings.

FIG. 1 is a schematic view of a working chamber (known per se) of a two-cycle engine of the present invention, FIG. 2 is an opening and closing angle diagram of an intake / exhaust valve of a normal two-cycle engine, and FIG. FIG. 4 is a diagram when the engine according to an embodiment of the invention is operated at low power (the angle), FIG. 4 is a diagram when the engine according to another embodiment of the invention is operated at the low power (the angle), FIG. 5 is a schematic diagram of an engine designed to operate according to FIG. 4, FIG. 6 is a schematic diagram of another engine designed to operate according to FIG. 4, first and foremost Refer to FIG.

The engine described in connection with the invention is a two-stroke engine with single or multiple working chambers of the type described in the aforementioned French patent 2,338,385. This working chamber shown in FIG. 1 comprises a moving piston, namely its piston rod 2, as well as a sliding piston 1, and a stationary piston, ie a cylinder 3 with a cylinder head 4 on its top. The cylinder head 4 is provided with an intake passage 5 and an exhaust passage 6, and an intake valve 7 that cooperates with the seat 8 and an exhaust valve 9 that cooperates with the seat 10.
It is designed to be opened and closed. Therefore, the cylinder 3 is not provided with a port on its lateral wall, and the seat 8
And 10 are arranged on the cylinder head 4.

The other parts of the engine, that is, the main shaft, the camshaft, and the rocker arm set are conventional ones, and thus detailed description thereof will be omitted. The inclination of the valve and its size are designed in the best mode so as to achieve the most effective performance possible under normal operating conditions, for example as shown in the aforementioned French patent 2,338,385.

FIG. 2 shows the normal operating mode of this engine. This drawing, whose origin is bottom dead center BDC, progresses clockwise. The angular positions are as follows: exhaust opening OE: -60 ° exhaust closing FE: + 100 ° intake opening OA: -30 ° intake closing FA: + 100 ° Therefore, exhaust valve after 120 ° downward stroke from top dead center 9 is open (OE), and the intake valve 7 is still closed for 30 ° corresponding to the blast period. After the intake opening (OA), the blast stage is followed by a 130 ° sweeping period, during which the intake passage 5 and exhaust passage 6 of the working chamber
The aerodynamic effect of the positive pressure differential between replenishes the filled air. The closing stage then continues for 200 ° and is asymmetrically divided in this example into a true compression stroke of 80 ° corresponding to a volume compression non-8 / 1, and a combustion-expansion stroke lasting 120 °, which is 12.9 / 1. It corresponds to the volume expansion ratio of.

This asymmetrical cycle makes it possible, as usual, to achieve high efficiencies in relation to certain powers which are also high powers.

Such a timing diagram can be achieved in a particularly normal manner with the help of a camshaft which is mechanically coupled to the shaft or crankshaft and which cooperates directly or indirectly with the valve and its elastic return device. The camshaft-valve cooperation can be mechanical (push rods, rocker arms, etc.) or achieved with other devices such as fluid transmissions.

Also, the angular position can be easily changed by a control device, such as a fluid or pneumatic jack or an electromagnetic jack.

In the present invention, these control devices are configured so that the opening and / or closing angular positions of the intake and exhaust valves can be changed with a large angle change during the operation of the engine.

By way of example, the connection between the camshaft and each valve may include a variable adjustment device (eg fluid pressure change in the gap, or displacement of the rocker arm axis), or between the cam and the camshaft, Or the connection between the cam and the shaft of the engine can be made variable in a manner known per se; the cam has a double cam profile and the transition of the camshaft changes from one profile to the other during the course of operation Camshafts made possible are available; if the valve is directly controlled by hydraulic, pneumatic or electromagnetic jacks, the angular open and closed positions of the valve are
It can be modified, for example, by means of a pilot device known per se which utilizes a detector of the shaft position of the engine.

Referring to FIG. 3, the first method of practicing the invention will be described.

In the present invention, the engine described as an example is operated by the two cycles of FIG. 2 as long as the engine operating parameter exceeds a predetermined threshold value. This parameter is, for example, the rotational speed of the crankshaft. When this rotation speed falls below this threshold,
The device according to the invention for controlling the valve is adapted to immediately correct the angular open and closed positions of the intake and exhaust valves according to FIG. In the latter case, d.
c. The angle (rotation angle of the crankshaft) is as follows. : OE: -120 ° FE: -90 ° OA: -90 ° FA: + 20 ° Therefore, as is apparent from this, the opening (OE) of the exhaust valve 9 is advanced by 60 ° toward the top dead center and 30 Deg., During which a partial exhaust of combustion gases takes place in the form of a blast during the exhaust, which is brought about by the expansion following the opening of the exhaust valve 9. At the end of this 30 °, the exhaust valve 9 is closed (FE).

In each case, OA, which is 30 ° in this example, and
The stagger angle between the OEs (as seen on the crankshaft) is
Greater than the 20 ° limit previously set.

Therefore, the scavenging period is omitted and the exhaust valve 9
Of intake valve 7 (OA) that occurs at the same time as closing (FE)
It is replaced by the intake period of fresh air, which lasts 110 °, which corresponds to half the maximum volume of the working chamber in terms of volume and 2/3 of the mass of fresh air in terms of mass. A proportion, which is sufficient to burn the fuel quantity corresponding to the idling operating conditions.

After closing the intake valve (FA), compression stage, top dead center (TD
Approaching C), combustion occurs, and the cycle is restarted.

The pressure level in the exhaust manifold has no effect because the intake and exhaust sections do not open at the same time, and an engine designed in this way ensures stable operation during start-up and idling, even if it is not supercharged. Will be possible.

Furthermore, the compression stroke starts near the bottom dead center BDC,
As a result, the volumetric compression ratio is increased to a value of 15.6 / 1 (instead of 8/1), so that even in the atmospheric suction associated with diesel engines, self-ignition of the air-fuel mixture is guaranteed.

In the first embodiment described herein, the timing diagram of FIG. 3 is easily implemented if a device that directly controls the valve by a fluid or electromagnetic jack is utilized.
In fact, it is possible to achieve high angular velocities for the opening and closing of the valves, in particular of the exhaust valve 9, when the rotational speed of the crankshaft is below the abovementioned threshold value. This opening and closing rate can be further increased by utilizing fluid coupling elements between the jack and the valve, which coupling elements are associated with conventional fluid timing devices and the rise of the valve. Can be omitted or shortened.

If a conventional valve controller (camshaft cooperating with an elastic controller) is utilized, the timing diagram of FIG. 3 shows the up and down cams for closing the valve, especially at relatively high speeds. Has a particularly steep slope, which is sometimes difficult to achieve.

In the case of an engine with a camshaft, the embodiment described according to FIG. 4 is therefore preferred.

In this embodiment, when the speed of rotation falls below a predetermined threshold, the camshaft is moved backward or counterclockwise by 60 ° to achieve the illustrated timing diagram as follows: OE: -120 ° FE: +40 ° OA: -90 ° FA: +40 ° As in the embodiment of Figure 3, the stagger angle between OA and OE is 30 °. However, for the engine shown in FIG. 3, the plast period is followed by a mixing period beginning with intake opening IO, in which intake valve 7 and exhaust valve 9 open simultaneously.

For example, in the case where the pressure in the exhaust manifold is higher than the intake pressure, in order to avoid the possibility of harmful backflow of exhaust gas from the exhaust manifold during the downward stroke of the piston to prevent stable idling of the engine, in this embodiment Is directed to an exhaust unidirectional device, such as a check valve, which is attached to a single or a pipe connecting each working chamber to an exhaust manifold, downstream of the exhaust valve.

These valves can be replaced by any equivalent device, for example a gas-dynamic diode arranged in said pipe.

In another embodiment of the invention, the timing diagram of the intake and exhaust valves is for example as shown in Fig. 4, i.e. the intake valve 7 and the exhaust valve 9 are open at the same time during at least the lowering of the piston. It is provided.

In a first modification of the above-described embodiment of the present invention, the gas outlet of a single or each working chamber is gassed by the pulse generated by the opening of the exhaust valve 9 and the blasting of gas at the end of the downward stroke. Backflow is avoided by utilizing the inertial effect of a gas column that is moved in a pipe that connects to the manifold.

This effect, known as the Kadenacy effect, requires a special configuration of pipe (diameter and length) for optimum conditions.

If the pipe 11 is open in the direction of gas flow in the straight exhaust manifold 12, as shown in FIG. 5, even if the engine is very slow and there is no cadencey effect, the exhaust manifold An exhaust blast with the form of pulses passing freely through 12 is achieved. As shown in FIG. 6, especially if the engine is equipped with a turbine 29 of a turbocompressor unit 28-29 at the end of the manifold 12, obstacles such as elbows, swirls or distributors are located in front of the turbine wheel. Otherwise, the blast described above, with some Pelton turbine effect, causes the turbocompressor unit to rotate sufficiently to provide ventilation in the working chamber 3 within the intake manifold 27, It enables reliable and flexible operation of the engine at the lowest operating conditions, and especially at start-up.

FIG. 5 shows an engine according to the invention, in which a block 13 in which an engine shaft or crankshaft 14 rotates is provided with three working chambers or cylinders 3 and an air filter 16 Is supplied from an air manifold 15 containing The intake valve 17 and the exhaust valve 18 are driven by the control device 21 via the camshafts 19 and 20. This engine includes a detector 22 for the rotational speed of the shaft 14, a detector 23 for the air intake pressure, a detector 24 for the amount of fuel introduced into the working chamber 3 via the fuel introduction device 25 in each cycle, and, optionally. It also includes an exhaust temperature detector 34. An electronic device 26 for adjusting the control device 21 is responsive to the detectors 22 and / or 23 and / or 24 and / or 34 and the value of the single or combined parameter detected by the single or multiple detectors. As a function of the result of comparison with the threshold value, the state of the control device 21 is adjusted according to the invention for a normal two-cycle operation or a modified operation.

As a modified example of the above-described embodiment of the present invention, the working chamber or the cylinder 3 is used when emptying another working chamber in the scavenging state.
The ejection effect brought about by the pulse resulting from is obtained. In this case, the number of working chambers must be 4 or more in consideration of the angular period of this process.

Such an engine is shown in FIG. 6, in which elements similar to those in FIG. 5 have the same reference numerals unless otherwise indicated.

The illustrated engine includes five working chambers 3, which are air intake manifolds 27 that receive supercharged pressure air from a compressor 28 of a turbo compressor unit.
Is supplied with air from the turbine of the unit
29 is driven by the exhaust gas, and the compressed air is first cooled by the air cooling device 30. The exhaust system 31 utilizes the ejection effect of gas.

This ejection effect is due to the French patent 2,378,178.
No. 2,415,200, No. 2,478,736.

In this type of arrangement shown in Figure 6, the following structural features are required: A-a pipe in the form of a converging or converging / diverging nozzle, the outlet of which is in the gas manifold. A very short connection of small volume between the outlet of the working chamber and the gas manifold 31 by means of a pipe 32 oriented in the flow direction of.

The very small volume of these pipes 32 and the constrained passage sections have the effect of helping to recover the energy available in the working chamber at the beginning of the exhaust blast stage. In fact, the pressure in the pipe rises rapidly upon opening of the exhaust valve and approaches the pressure in the working chamber, so that the energy loss due to the throttle when passing through said exhaust valve is considerably reduced.

As a result, the maximum available energy available in the working chamber at the end of expansion is stored.

Due to the acceleration in the confinement pipe 32 and the orientation of the pipe in the flow direction in the gas manifold 31, this potential energy is effectively converted into kinetic energy, which leads to the acceleration of the gas column flowing in the manifold 31. Have contributed.

B-Collecting exhaust gas from multiple working chambers in a gas manifold 31 having a diameter (generally half the order) smaller than the diameter of the piston.

Manifold dimensions are represented as follows: Where Se = cross section of gas manifold, Sp = cross-sectional surface area of each piston, n = number of pistons, n · Sp = total surface area of pistons in a cylinder connected to the same gas manifold, Vp = average velocity of each piston, Ve = the gas manifold downstream end of the gas velocity, [rho _{'2 =} density of the intake air, [rho _{5 =} density of the exhaust gas, the flow coefficient alpha = engine (0.5 to 1.2), Mach number of the gas flow in the manifold downstream end: here, T ₅ = exhaust gas temperature (° K) If, T ₅ = 873 ° _{K (600 ℃), a 5} = 577m / s if m = 0.3, and Ve = 173m / s C- momentum from the working chamber Ignition of different working chambers grouped in the same gas manifold in order to systematize the injection as regularly as possible and to minimize exhaust from one chamber to disturb the other. Adjusting the order.

D-To prevent the total pressure of the fast flow from dropping due to friction or path changes (bends or abrupt changes in cross section) between the downstream end of the manifold (in the gas flow direction) and the turbine inlet. The connections between should be as simple and short as possible; by way of example, the total pressure drop due to friction of a Mach number 0.7 gas flow is of the order of 1% per unit length with respect to the manifold diameter.

Between the downstream end of the E-gas manifold and the inlet of the turbine, optionally intervening a diffuser capable of slowing the flow down to a Mach number of the order of 0.25.

But before this flow enters the turbine wheel,
Due to the fact that it is accelerated again to a Mach number of the order of 1 (usually in a fixed nozzle ring called a distributor), the process of slowing down in this diffuser and then accelerating in the distributor is omitted and feature E is It is preferable to substitute the following features.

E'-Organizing the housing for admission of gas to the turbine so that the velocity of the gas remains substantially constant until it enters the expansion wheel of the turbine.

When the engine of the present invention is in the low power operating mode, advancing the opening of the exhaust valve, i.e., advancing 60 ° in the previously described embodiment, 120 ° before BDC, i.e. before the end of the expansion stroke of the piston. Initiating the opening of the exhaust valve (OE) offers many advantages, including: Exhaust blasting due to the high pressure and temperature in the working chamber and the high mass of gas released due to the opening of the exhaust valve. Is more active: the drive and acceleration of the supercharged turbine are greatly improved, and this is especially the case when the exhaust system is constructed according to the second embodiment of the invention described above.

For the same reason, the self-scavenging of a two-cycle engine is improved during low power operation of the engine.

For a given power to the main shaft, a reduction in the expansion transfer will lead to an increase in fuel consumption and thus an increase in the temperature of the gas leaving the working chamber, a factor which is also favorable for driving a supercharged turbine. Is.

The direct connection 33 between the linear manifold and the inlet of the turbine 29 allows the ejector or inertial effect to generate sufficient draft to achieve good scavenging by the turbocompressor unit, even at the lowest speeds. In the absence, it benefits from the pulse by exhaust blast.

The present invention is, of course, subject to many modifications, and the various intake and exhaust timing diagrams described above have been described essentially by way of example, and these diagrams are also modified within the scope of the invention. It is possible to

Claims (27)

[Claims] 1. An internal combustion engine operating in two cycles, comprising at least one variable volume working chamber (3) defined by a piston in a cylinder without lateral ports, said working chamber (3). An external scavenger for starting and performing low-power operation is provided in an engine in which an intake valve (7) and an exhaust valve (9) that are synchronized with the rotation of the engine shaft are provided in the air intake and gas exhaust portions of the engine. At least one of the engine, by means of a control device, which is not provided, the intake and exhaust valves (7, 9) being able to be changed as a function of the angular position of the valve opening and possibly its closing as seen from the engine shaft. Is actuated as a function of two operating parameters, the control device being responsive to the operating parameters of the engine. At the time of start-up and low-power operation,
For normal operating conditions, while advancing the opening time of the intake valve and maintaining it until after the opening of the exhaust valve, a sufficient amount of fresh air is introduced into the single or each working chamber under all operating conditions An internal combustion engine characterized by being able to do so. 2. A start-up and low power operation, wherein the stagger angle between the opening of the intake valve and the opening of the exhaust valve is at least 30 °. Engine. 3. A turbo compressor for supercharging, a gas inlet of the turbine communicating with an exhaust of a working chamber, and an air outlet of a compressor mechanically driven by the turbine. The engine according to claim 2, wherein the engine is communicated with an air intake portion of the chamber. 4. The parameters related to the operation of the engine are:
In the case of a supercharged two-cycle engine, the supercharging pressure value, or the amount of fuel introduced into a single or multiple working chambers per cycle, or the engine main shaft speed, or the exhaust temperature, or between the intake and exhaust pressures. The engine according to claim 1, characterized in that an effective differential pressure is provided and a device for detecting the parameter value is provided. 5. The control device is mechanical and is adapted to be driven directly by the main shaft of the engine via an operating chain, in particular a camshaft, and associated valves (7,9). Engine according to claim 1, characterized in that a mechanical adjustment device is provided for correcting the angular position of the opening and optionally closing of the engine. 6. A control device for the valve (7,9) is of electrical, hydraulic or pneumatic type, and a regulating device responsive to the parameter is associated with the control device, the valve (7,9) being associated with the control device. ) The opening and optionally closing the angular position of the opening is modified.
The engine described in paragraph. 7. When the control device is used, the angular position of the opening and optionally closing of the intake and exhaust valves (7, 9) is predominantly intake during at least part of the stroke associated with the increase in the volume of the working chamber. Engine according to claim 1, characterized in that the valve (7) is modified so as to provide an air intake action. 8. An engine according to claim 7, characterized in that, when the control device is used, the compression ratio corresponds to a single compression stroke or the entire compression stroke of each piston. 9. The engine according to claim 7, wherein the intake valve is opened at a single position or near an intermediate position between strokes of the pistons. 10. The control device according to claim 9, characterized in that the control device is arranged such that the intake and exhaust valves (7, 9) do not open at least approximately at the same time. Engine. 11. The controller is configured to simultaneously open the intake and exhaust valves (7, 9) during a portion of the engine cycle, and to the exhaust system of the engine from the exhaust system. Engine according to claim 7, characterized in that a unidirectional device is arranged which limits or prevents the possibility of backflow of gas. 12. The engine according to claim 11, wherein the unidirectional device is a mechanical checking device. 13. The unidirectional device is a fixed exhaust pipe having a length sufficient to utilize an inertial effect of a gas column moved in the pipe.
The engine described in paragraph. 14. A device comprising four or more working chambers and utilizing the ejection effect provided by a gas pulse from one working chamber when emptying another working chamber in a scavenging state. The engine according to claim 11, characterized by: 15. A gas outlet from the working chamber is connected to the gas manifold, and an exhaust pipe having a shape of a converging or converging / diverging nozzle is provided, and the outlet is a gas in the manifold. Engine according to claim 14, characterized in that it is oriented in the same direction as the flow. 16. The scope of claim 12 wherein the exhaust pipe is opened in the same direction as the gas flow in the gas manifold and is preferably coaxially arranged with respect to the gas manifold. Engine described. 17. An exhaust system having a portion for directly connecting an exhaust valve (9) and a wheel of a supercharging turbine (29), and rotationally driving a turbo compressor unit only by an exhaust blast pulse during low power operation. The engine according to claim 3, characterized in that. 18. A cross section of the passage of the gas manifold is substantially constant, and the cross section is sufficiently small so that the gas flow velocity at the downstream end of the manifold exceeds Mach number 0.4 in the nominal operating state. Characterized by,
The engine according to claim 15. 19. The downstream outlet of the gas manifold is 0.4
The invention is characterized in that it is connected to an inlet of a turbine of a supercharged turbo compressor unit through a diffusing device that reduces the speed to a smaller Mach number.
Supercharged engine according to paragraph. 20. The gas manifold downstream outlet is in direct communication with the supercharged turbo compressor gas inlet, and the gas velocity is not significantly reduced between the manifold outlet and the turbine rotor inlet. 18. The engine according to claim 17, further comprising a gas distribution spiral device. 21. At least one variable volume working chamber (3) defined by a piston in a cylinder without lateral ports and operating in two cycles, air intake and gas discharge of said working chamber (3). An internal combustion engine having an intake valve (7) and an exhaust valve (9), which are synchronized with rotation of an engine shaft,
Intake and exhaust valves (7,9) without external scavenger for starting and low power operation
Is actuated as a function of at least one operating parameter of the engine by means of a control unit which, as seen from the shaft of the engine, can be modified as a function of the angular position of opening and possibly closing of said valve, In response to the operating parameters of the engine, the control device advances the start time of opening the intake valve with respect to a normal operating condition during start-up and low-power operation, and
A method for operating an internal combustion engine, which is maintained until after the opening of an exhaust valve is started so that a sufficient amount of fresh air can be introduced into each working chamber or under any operating condition. Or when the parameters have values that correspond to the normal or nominal operating conditions of the engine, the engine is operating in two-cycle normal operation consisting of: -the intake and exhaust valves (7,9) are closed. Compression-combustion-expansion stage, while the pulse discharge period at the end of the expansion stage, during which only the exhaust valve (9) is open, the intake valve (7) and the exhaust valve (9) at the same time. A scavenging period in which the combustion gas is open and at least partially exchanged with fresh air by the action of a single or an average positive pressure difference in each working chamber, b) while said single Or multiple parameters have values that correspond to operating conditions in which the engine cannot rotate or operate properly, the valve (7, 9) opening angular position is relative to the maximum volume position of the working chamber. And operating the engine so that the working chamber and the intake system of the engine are communicated with each other during at least a part of the volume increasing period of the working chamber. 22. The open position of the intake and exhaust valves is advanced so as to mainly utilize a part of the volume increasing stroke of the working chamber in the intake process of air. The method described. 23. A unidirectional device is utilized in the exhaust system, especially in the pipe, to substantially prevent backflow from the exhaust system to the working chamber. The method described in. 24. The invention is characterized in that the intake closing and opening angular positions are different from each other near each other so that the intake valve (7) and the exhaust valve (9) are prevented from being simultaneously opened. The method described in paragraph 22. 25. Claims 21 to 24, characterized in that the open and closed positions of the intake and exhaust valves all have staggered angles, in particular due to the angular phase displacement of the camshaft. The method described in either. 26. An asymmetric timing angle diagram is used to open and close the intake and exhaust valves so that the angular position of intake and exhaust closure is farther from bottom dead center BDC than the open angular position of the intake and exhaust valves. The method according to any one of claims 21 to 25, characterized in that 27. The engine according to any one of claims 21 to 26, wherein the engine is supercharged by a turbo compressor and the supercharged turbo compressor is accelerated before starting the engine. The method described in crab.